An Automatic Optical Inspection (AOI) system for optical inspection of imaging devices used in automotive industry using an inspecting optics of lower spatial resolution than the device under inspection is described. This system is robust and with no moving parts. The cycle time is small. Its main advantage is that it is capable of detecting and quantifying defects in regular patterns, working below the Shannon-Nyquist criterion for optical resolution, using a single low resolution image sensor. It is easily scalable, which is an important advantage in industrial applications, since the same inspecting sensor can be reused for increasingly higher spatial resolutions of the devices to be inspected. The optical inspection is implemented with a notch multi-band Fourier filter, making the procedure especially fitted for regular patterns, like the ones that can be produced in image displays and Head Up Displays (HUDs). The regular patterns are used in production line only, for inspection purposes. For image displays, functional defects are detected at the level of a sub-image display grid element unit. Functional defects are the ones impairing the function of the display, and are preferred in AOI to the direct geometric imaging, since those are the ones directly related with the end-user experience. The shift in emphasis from geometric imaging to functional imaging is critical, since it is this that allows quantitative inspection, below Shannon-Nyquist. For HUDs, the functional detect detection addresses defects resulting from the combined effect of the image display and the image forming optics.

We present a flexible fluorescence lifetime imaging device which can be employed to scan large sample areas with a spatial resolution adjustable from many micrometers down to sub-micrometers and a temporal resolution of 20 picoseconds. Several different applications of the system will be presented including protein microarrays analysis, the scanning of historical samples, evaluation of solar cell surfaces and nanocrystalline organic crystals embedded in electrospun polymeric nanofibers. Energy transfer processes within semiconductor quantum dot superstructures as well as between dye probes and graphene layers were also investigated.

The synthesis and characterization of new chromophores with second-order nonlinearities
containing thienylpyrrole 1a, 2a-b, bithiophene 3 and arylthiophene 4 as π-conjugated bridges and
indanonedicyanovinyl acceptor group are reported. The effect of placing the acceptor group at
thiophene or pyrrole rings on the optoelectronic properties was also evaluated for thienylpyrrole
derivatives 1a and 2a-b. The linear optical properties (absorption and emission) for all compounds
were evaluated in dioxane solutions. In addition, the hyperpolarizabilities β of chromophores 1-4
were measured using hyper-Rayleigh scattering in dioxane solutions and thermogravimetric analysis
(TGA) was used to evaluate their thermal stability. The experimental results indicate that
chromophores 1-4 are endowed with both excellent optical nonlinearities and high thermal stability
making them interesting candidates for nonlinear optical (NLO) applications.

Two series of novel push-pull heterocyclic azo dyes have been synthesized and characterized. The two series of
compounds were based on different combinations of π-conjugated bridges (bithiophene and thienylpyrrole) which also
act simultaneously as donor groups, together with diazo(benzo)thiazolyl as acceptor moieties. Their thermal stability and
electrochemical behavior were characterized, while hyper-Rayleigh scattering (HRS) was employed to evaluate their
second-order nonlinear optical properties. The results of these studies have been critically analyzed together with several
thienylpyrrole azo dyes reported earlier from our laboratories in which the thienylpyrrole system was used as the donor
group functionalized with aryl and (benzo)thiazolyldiazene as acceptor moiety. The measured molecular first
hyperpolarizabilities and the observed linear optical and redox behavior showed strong variations in function of the
heterocyclic spacers used (bithiophene or thienylpyrrole) and were also sensitive to the acceptor strength of the
diazenehetero(aryl) moiety.

Optical microscopy as a means to identify graphene is hampered by the low absorptivity of its monolayers and few-layer
structures. However for many of the upcoming applications for graphene, it is essential to develop techniques to readily
deliver images of graphene based structures. We report on two novel techniques and additionally on a well-known, but
modified technique for the identification of graphene. All of the described methods employ standard optical reflection
and transmission microsocopy and can be readily adapted in most laboratories. One of the novel techniques is based on
the enhancement of the optical contrast by refractive index matching using oil immersion microscopy. The second
technique, microdroplet condensation, exploits the hydrophobicity difference between the carbonic sheets and almost
any arbitrary substrate. The third technique is a modification of the already well known technique to enhance the
visibility contrast of graphene using interferometric effects by employing a Si wafer coated with a dielectric of specific
thickness.

A series of novel donor-acceptor chromophores designed to have good second order nonlinear optical responses has been
synthesized and characterized. This series of compounds was designed to explore the consequence of using different
electron accepting moieties which were linked through an arylthiophene bridge to a pyrrole heterocycle that plays the
role of an auxiliary donor group. These new push-pull chromophores have been extensively characterized using cyclic
voltammetry, thermogravimetric analysis and hyper-Rayleigh scattering (HRS) in solution. The measured molecular first
hyperpolarizabilities and the observed electrochemical behavior showed that they were very sensitive to the acceptor
strength of the acceptor moieties. Moreover, the combination of their good nonlinearity and high thermal stability make
them good candidates for potential device applications.

We present experimental results on optical properties of the human skin controlled by administration ofthe 40%-glucose
solution. In vivo reflectance spectra of the human skin were measured. Results of the experimental study of influence of
the 40%-glucose solution on reflectance spectra of the human skin are presented. A significant decrease of reflectance of
the human skin under action of the osmotic agent is demonstrated. The experiments show that administration of the
glucose solution allows for effective control of tissue optical characteristics, that makes skin more transparent, thereby
increasing the ability of light penetration through the tissue. Laser Doppler flowmetry has been used for study of skin
blood microcirculation under the action of the glucose solution. Results of the experiments demonstrated that at the
action of the glucose solution blood perfusion and blood concentration increase, however the mean blood velocity does
not change. The presented results can be used in developing functional imaging techniques, including OCT and
reflectance spectroscopy. A potential benefit of the optical clearing technique is the improvement of laser therapeutic
techniques that rely on sufficient light penetration to a target embedded in tissue.

The investigation of blood dynamical characteristics in the skin under the action of 40% glucose solution was performed in vivo by the laser Doppler technique. Experiments demonstrate that glucose solution affects significantly the blood perfusion and concentration. Qualitative explanation was made for observed perfusion dynamic effect in the skin dermis based on the following factors: tissue cells shrinkage and additional capillaries opening under osmotic stress. The size of glucose vesicle lens was measured under the skin by ultrasonography. The analysis of vesicle sizes monitoring leads to the conclusion that glucose lens spread, basically, along the skin than in the perpendicular to the skin surface direction. Obtained results show the significant anisotropic perturbation of the dynamic characteristics of blood in vascular plexus under the optical active solution influence that must be taken into consideration during optical clarification of biological tissues.

Cesium hydrogen L-malate monohydrate, CsH(C4H4O5).H2O, is a new non-linear optical semi-organic crystalline material with a second harmonic generation efficiency roughly 2.5 times greater than KDP. Its crystal structure, space group P21, shows that the malate anions, are interconnected through directional O-H•••O hydrogen bonding, in a head-to-tail arrangement, creating extended anionic layers. The water molecules provide a cross-link, through hydrogen bonding, between adjacent layers. Especially noteworthy is that the Cesium cations and the COO- group from the malate anions, form a sequence of nearly perfectly aligned dipoles oriented along the b crystallographic axis giving a permanent dipole moment of 38 Debye per unit cell. As the crystals are non hygroscopic and easy to grow, they are potential new material for nonlinear optical and pyroelectric applications.

The backscattered intensity from low-intensity laser illumination of the skin in the area of vascular plexus is investigated in vivo. The exposure of blood to low power laser light in the absorption range of haemoglobin leads to increasing intensity of the backscattered light. Theoretical evaluation using an existing optical model of erythrocyte aggregation has suggests that the fragmentation of erythrocyte aggregates is the most probable mechanism leading to the enhanced backscattering.

The intensity of light backscattered when low-power laser radiation is incident on the skin is investigated under in vivo conditions. The exposure of blood to low-power laser light in the absorption range of haemoglobin leads an increased intensity of the backscattered light. The theoretical calculation using the existing optical model of erythrocyte aggregation has suggest that the fragmentation of erythrocyte aggregates is it most probable mechanism leading to the enhanced backscattering.

For the purpose of determining how the physical and chemical parameters of blood influence the fluctuation spectra S (ω) under multiple scattering conditions, a series of experiments were made using specimens of both whole blood and blood diluted by plasma and serum in different proportions. Measurements of the viscosity of whole blood and the prepared specimens as well as the erythrocyte sedimentation rate (ESR) were made by standard methods. The variance estimates of the mathematical model coefficients were made. It is shown that variance estimates depend strongly on the viscosity and ESR of whole blood.

The influence of low-intensity laser irradiation on backscattered radiation from the skin vascular plexus is investigated in vivo. Laser irradiation of the blood in the absorption range of haemoglobin leads to an increase in the intensity of the back-scattered emission. The calculated temperature gradients are sufficient to produce structural and conformational changes in the cellular proteins of the erythrocytes and/or to produce a change in the permeability of membrane and cause the disaggregating of the aggregates of erythrocytes. A theoretical calculation for the increase in the intensity of the back-scattered emission with the disaggregating of erythrocytes was performed.

The influence of low-intensity laser radiation on the transport of human blood within skin capillaries is investigated in vivo on cardiac ischemia patients. For the sample as a whole the mean blood perfusion increased by thirty percent after exposure, for 10 minutes, to light from a Helium Neon laser at an irradiance level of 225 W/m2. In some individual patients the blood perfusion more than doubled. A two-dimensional theoretical model is developed that suggests that modest heating of the blood is induced by the incident radiation and could be responsible for the observed increase.

Theoretical and experimental studies of the influence of low-intensity laser radiation, on the velocity of microcirculation of the erythrocytes of patients with the cardiovascular disease “in vivo" are carried out. Dynamic light scattering techniques were used to monitor the variation in the perfusion of micro capillary blood flow during irradiation under "in vivo" conditions and compared to the change in average size of aggregates of the blood effects observed "in vitro" using static scattering of light. It is shown that the process of the fragmentation of erythrocytes depends on amount of energy absorbed by biological tissues. This conclusion is supported by the good qualitative agreement with the theoretical model, based on the heat transfer theory within the dermis.

The method of dynamical spectroscopy the change in sizes of aggregates of bile vesicules caused by different nucleating factors has been investigated. It is shown that the bile vesicule sizes at chronic cholecystites vary from 90-200 nm. In so doing, the presence of a large fraction of bile vesicules characterized, as shown in the paper, by a higher concentration of cholesterol can serve as a criterion for cholestitis acuteness and litogenesis intensity.

In this communication we present a study regarding the limitations that geometry imposes on the degree of phase matching attainable in a self-diffraction experiment. We find that to generate a strong signal the effective area over which the incident beam are superposed within the nonlinear medium must contain spatial variations on a length scale equal to the inverse of the phase mismatch. We develop a simple model that allows us to interpret the generated signal in terms of a sum over contributing phasors from each plane of constant phase within the active region. The phasors tend to add together to create a spiral figure reminiscent of Cornu Spirals in diffraction theory.

For nonlinear optical materials in which the excitation diffuses significantly during the time scale of measurement the usual analysis of a Z-scan experiment must be modified. We develop a simple first order theory based on a quadratic rather than Gaussian spatial modulation of the index of refraction. This leads to asymmetric Z-scan curves. We apply this theory to the study of the thermal-optic effect in a simple neutral density filter. A significant spatial phase chirp can be induced in these filters at modest intensities. The observed transmission curves agree well with the quadratic theory.

Crystals of para-nitroaniline were grown from solution while subjected to a strong dc electric field of 2 X 105 V/m. This resulted in a modification of the unit cell lattice parameters and space group with respect to crystal grown in the absence of an electric field. The modified crystal are capable of generating a second harmonic signal and poses a significantly lower dielectric permittivity.

The nonlinear optical properties of sodium di-2- ethylhexysulfosuccinate (AOT)-water-isooctane microemulsions are studied as a function of reverse micelluar size. Extremely large nonlinear optical effects are observed far away from the critical temperature for phase transitions. We propose that this is due to a combination of electro- strictive and thermo-diffuse effects.

We have characterized the transverse spatial dependence of the real and imaginary parts of the complex nonlinear refractive index of a semiconductor doped glass filter, which exhibits absorptive bistability. Using the Z-scan technique, combined with an interferometric measurement of the integrated optical thickness, we are able to fit the observed experimental data assuming a quadratically varying transverse temperature profile in the sample. The transverse variations in the nonlinear refractive index do not scale directly with the size of the incident beam, but exhibit marked asymmetries depending on whether the incident beam is converging or diverging.

We used a modified form of the Z-scan technique to study the various factors influencing bistability in a semiconductor doped glass filter. A strong self-focusing effect was observed and an estimate of the corresponding n2 coefficient is obtained. A systematic modeling of absorptive bistability in a semiconductor doped glass, including both longitudinal and transverse heat diffusion as well as the effects of self-focusing, is presented and compared with experimental observations.

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